System and method for controlling power in a communication system

ABSTRACT

A method for controlling power in a communication system. The power control method in a base station includes receiving channel information from a plurality of mobile stations, and generating power control information of the mobile stations according to the received channel information; mapping the generated power control information to transmission fields of corresponding mobile stations according to allocation information of channels allocated to receive the channel information; and broadcasting to the mobile stations a message including the power control information mapped to the transmission fields of the corresponding mobile stations.

PRIORITY

This application claims priority under 35 U.S.C. § 119(a) to a KoreanPatent Application filed in the Korean Intellectual Property Office onJun. 16, 2006 and assigned Serial No. 2006-54515, the disclosure ofwhich is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to a communication system, andin particular, to a system and method for controlling power of a MobileStation (MS) in a communication system.

2. Description of the Related Art

Extensive research on next generation communication systems are beingconducted to provide users with high-speed services having variousQuality of Service (QoS) levels. Meanwhile, power control schemes usedin current communication systems can normally be classified as downlink(forward) power control schemes and uplink (reverse) power controlschemes according to direction of power control, and can be classifiedas open-loop power control schemes and closed-loop power control schemesaccording to whether a transmitter, or a Base Station (BS), receivesfeedback information from a receiver, or an MS.

In downlink power control schemes, power control is performed in a BS.When the channel condition is good as a distance between the BS and anMS is short, i.e. as the MS is located in a center area of the BS, or asthere is no shadowing due to obstacles, the BS allows the MS to transmitsignals with minimum possible transmission power, thereby reducinginterference to neighboring BSs. When channel conditions are poor, theBS increases power of transmission signals as high as needed within apossible range so the MS may normally receive transmission signals fromthe BS. In uplink power control schemes, power control is performed inan MS. The MS serves as a transmitter and the BS serves as a receiver,and they control power in the same manner as that in downlink powercontrol schemes.

In open-loop power control schemes, a transmitter (BS or MS) performingpower control, independently determines channel quality of a receiver(MS or BS), and performs power control depending on the channel quality,and open-loop power control scheme control power based on reversibilitybetween downlink and uplink channels. Reversibility between downlink anduplink channels, as used herein, means that MSs having the same (orsimilar) location with respect to a BS will experience similar pathattenuation due to similar path attenuation based on a distance from theBS, the similar antenna gain based on antenna patterns, similarshadowing effect by the topology, similar multi-path fading, etc. Thatis, in open-loop power control schemes, based on reversibility betweendownlink and uplink channels, a transmitter spontaneously estimatessignal reception quality of a receiver, calculates necessarytransmission power depending on the estimated signal reception quality,and then transmits signals with the calculated transmission power.

In closed-loop power control schemes, unlike in open-loop power controlschemes, a transmitter controls necessary transmission power based onsignal reception quality of a receiver from which it has received afeedback channel, without independently determining a channel quality.In such a closed-loop power control scheme, overhead for feedbackchannels occurs undesirably. However, because a transmitter can acquireinformation on the channel quality at the receiver, a closed-loop powercontrol scheme can accurately control power of transmission signals, ascompared to an open-loop power control scheme.

However, in a typical communication system, as a number of MSs receivingcommunication services from a BS increases, a closed-loop power controlscheme suffers from an increase in an amount of channel qualityinformation that the BS should receive from MSs over a feedback channel.In addition, a closed-loop power control scheme suffers from an increasein overhead of a feedback channel allocated for receiving channelquality information. Further, in a typical communication system, when aBS transmits power control information of MSs to the MSs according tochannel quality information fed back from the MSs, an increase in anumber of MSs increases an amount of power control information that theBS should transmit to the MSs, and the increase in the amount of powercontrol information for the MSs causes an increase in overhead in thecommunication system. Therefore, a need exists for a power controlscheme for reducing overhead in communication systems.

SUMMARY OF THE INVENTION

The present invention addresses at least the problems and/ordisadvantages and provides at least the advantages described below.Accordingly, an aspect of the present invention is to provide a systemand method for controlling power in a communication system.

Another aspect of the present invention is to provide a system andmethod for controlling power of an MS to reduce overhead in acommunication system.

Another aspect of the present invention is to provide a system andmethod for transmitting power control information for controlling powerof an MS in a communication system.

According to an aspect of the present invention, there is provided amethod for controlling power in a communication system. The powercontrol method in a base station includes receiving channel informationfrom a plurality of mobile stations, and generating power controlinformation of the mobile stations according to the received channelinformation; mapping the generated power control information totransmission fields of corresponding mobile stations according toallocation information of channels allocated to receive the channelinformation; and broadcasting to the mobile stations a message includingthe power control information mapped to the transmission fields of thecorresponding mobile stations.

According to another aspect of the present invention, there is provideda method for controlling power in a communication system. The powercontrol method in a mobile station includes receiving a messageincluding power control information from a base station, and detectingpower control information included in the message; and detecting powercontrol information corresponding to the base station from the detectedpower control information according to allocation information of achannel allocated to transmit channel information of the mobile stationto the base station.

According to a further aspect of the present invention, there isprovided a method for transmitting control information for at least onemobile station in a communication system. The transmission method in abase station includes receiving channel information from at least onemobile station; generating control information of mobile stationsaccording to the received channel information; mapping the generatedcontrol information to transmission fields of corresponding mobilestations according to allocation orders of channels for the at least onemobile station, allocated to receive the channel information; andbroadcasting, to the mobile stations, a message including transmissionfields to which the control information of the corresponding mobilestations is mapped.

According to yet another aspect of the present invention, there isprovided a system for controlling power in a communication system. Thepower control system includes a base station for receiving channelinformation from a plurality of mobile stations, generating powercontrol information of the mobile stations according to the receivedchannel information, mapping the generated power control information totransmission fields of corresponding mobile stations according toallocation information of channels allocated to receive the channelinformation, and broadcasting to the mobile stations a message includingthe power control information mapped to the transmission fields of thecorresponding mobile stations.

According to still another aspect of the present invention, there isprovided a system for controlling power in a communication system. Thepower control system includes a mobile station for receiving a messageincluding power control information from a base station, detecting powercontrol information included in the message, and detecting power controlinformation corresponding to thereto from the detected power controlinformation according to allocation information of a channel allocatedto transmit channel information of the mobile station to the basestation.

According to yet another aspect of the present invention, there isprovided a system for controlling power in a communication system. Thepower control system includes a base station including a power controlinformation generator for receiving channel information from a pluralityof mobile stations, and generating power control information of themobile stations according to the received channel information; a channelallocator for allocating channels to the mobile stations to receive thechannel information; a power control bit sequence generator for mappingthe generated power control information to transmission fields ofcorresponding mobile stations according to allocation information of theallocated channels, and generating a power control bit sequenceaccording to the power control information mapped to the transmissionfields of the corresponding mobile stations; and a message generator forgenerating a message including the generated power control bit sequence,wherein the base station broadcasts the generated message to the mobilestations.

According to still another aspect of the present invention, there isprovided a system for controlling power in a communication system. Thepower control system includes a mobile station including a firstdetector for receiving a message including power control informationfrom a base station, and detecting the power control informationincluded in the message; a decider for checking allocation informationof a channel allocated to transmit channel information of the mobilestation to the base station; and a second detector for detecting, fromthe detected power control information, power control informationcorresponding thereto according to allocation information of theallocated channel, wherein the mobile station controls power of themobile station according to the power control information detected bythe second detector.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features and advantages of the presentinvention will become more apparent from the following detaileddescription when taken in conjunction with the accompanying drawings inwhich:

FIG. 1 is a schematic diagram illustrating a frame structure in acommunication system according to the present invention;

FIG. 2 is a schematic diagram illustrating a structure of an Uplink(UL)-MAP message field of a frame in a communication system according tothe present invention;

FIG. 3 is a diagram illustrating a burst allocation information fieldand a power control information field in a MAP message field of a framein a communication system according to the present invention;

FIG. 4 is a diagram illustrating a power control bit sequence for powercontrol in a communication system according to the present invention;

FIG. 5 is a diagram illustrating allocation of Channel QualityInformation Channels (CQICHs) over which a BS receives Channel QualityInformation (CQI) from MSs in a communication system according to thepresent invention;

FIGS. 6A and 6B are diagrams illustrating a method of mapping powercontrol information to corresponding MSs according to CQICH allocationinformation of the MSs in a communication system according to thepresent invention;

FIGS. 7A and 7B are diagrams illustrating a method of mapping powercontrol information to corresponding MSs according to CQICH allocationinformation of MSs in a communication system according to the presentinvention;

FIG. 8 is a diagram illustrating an operation in which a BS controlspower of MSs in a communication system according to the presentinvention;

FIG. 9 is a diagram illustrating an operation of controlling power by anMS in a communication system according to the present invention;

FIGS. 10A and 10B are schematic diagrams illustrating a power controllerof a BS in a communication system according to the present invention;and

FIG. 11 is a diagram illustrating a power controller of an MS in acommunication system according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Preferred embodiments of the present invention will now be described inwith reference to the drawings. In the following description, adescription of known functions and configurations incorporated hereinhas been omitted for clarity and conciseness.

The present invention provides a system and method for controlling powerin a communication system, for example, an Institute of Electrical andElectronics Engineers (IEEE) 802.16 communication system, which is aBroadband Wireless Access (BWA) communication system. Although thepresent invention will be described herein with reference to an IEEE802.16 communication system employing Orthogonal Frequency DivisionMultiplexing (OFDM)/Orthogonal Frequency Division Multiple Access(OFDMA), by way of example, a power control system and method providedin the present invention can also be applied to other communicationsystems.

In addition, the present invention provides a system and method forcontrolling power when a communication system exchanges data between aBase Station (BS) in charge of a particular cell and a Mobile Station(MS) that is located in the cell and receives a communication servicefrom the BS. The present invention, described below, provides a powercontrol system and method in which a BS in charge of a particular celltransmits, to an MS receiving a communication service therefrom, powercontrol information for controlling power of the MS in a communicationsystem employing OFDM/OFDMA.

The present invention provides a communication system in which a BS incharge of a particular cell generates power control information of MSsaccording to channel information of MSs, fed back from MSs located inthe BS cell, i.e. Channel Quality Information (CQI), for example,Signal-to-Interference and Noise Ratio (SINR) or Carrier-to-Interferenceand Noise Ratio (CINR) that the MSs have calculated and transmitted tothe BS; maps the generated power control information to correspondingMSs according to allocation information of Channel Quality InformationChannels (CQICHs) allocated to the MSs to receive the CQI feedback; andthen transmits a message with power control information to the MSs. Inother words, the BS broadcasts the message to the MSs, and upon receiptof the broadcasted message, each of the MSs detects power controlinformation corresponding thereto, and then controls power of theassociated MS according to the detected power control information.

Further, in a communication system according to the present invention,for power control for a plurality of MSs in a particular cell, a BSgenerates power control information of the MSs according to CQIs of theMSs, generates a power control bit sequence Power_Control_Bit_Sequenceaccording to the generated power control information, maps the powercontrol information to the MSs according to CQICH allocationinformation, i.e. maps the power control bit sequence to the MSs, andthen broadcasts a message with the power control bit sequence to theMSs. Upon receipt of the message, each of the MSs detects its own powercontrol information included in the message, and controls powerassociated with the MS depending on the detected power controlinformation.

As a result, in the communication system according to the presentinvention, even though a number of MSs are located in a particular cell,the BS in charge of the particular cell can minimize an increase inoverhead by transmitting power control information over one burst fieldindependently for individual frames of the MSs. In addition, the BS cancontrol power of the MSs at high speed by transmitting power controlinformation over one burst field independently for individual frames ofthe MSs.

A scheme in which a BS transmits power control information of the MSs,generated depending on CQIs of the MSs, in a message can be classifiedas a scheme of transmitting power control information in a Fast PowerControl (FPC) message in a form of a Medium Access Control (MAC)message, a scheme of transmitting power control Information Elements(IEs) in Uplink MAP (UL-MAP) IEs of a UL-MAP message, and a scheme oftransmitting Fast Tracking IEs in UL-MAP IEs of the UL-MAP message.These messages including power control information of the MSs arebroadcasted to all MSs located in the cell.

In addition, a scheme in which the BS transmits in the above-describedmessages a power control bit sequence of the power control informationgenerated depending on CQIs received from the MSs can be classifiedherein into a scheme of transmitting the power control bit sequence in apower control message in the form of a MAC message, a scheme oftransmitting the power control bit sequence in a MAP message, forexample, Downlink MAP (DL-MAP) message or UL-MAP message, and a schemeof transmitting the power control bit sequence in DL-MAP IEs or UL-MAPIEs of a MAP message, for example, DL-MAP message or UL-MAP message.Similarly, these messages including therein the power control bitsequence are broadcasted to all MSs located in the cell.

With reference to Table 1, a description will now made of an FPC messageincluding the power control information. Table 1 shows a format of anFPC message including power control information.

TABLE 1 Syntax Bits Notes Fast_Power_Control Message Format{  ManagementMessage Type = 38 8 bits  Number of stations 8 bits  Power measurementframe 8 bits   for(n=0;n<Number of stations;n++){    Basic CID 16 bits    Power adjust 8 bits   } }

As shown in Table 1, the FPC message includes a ‘Management MessageType’ field indicating a type of a corresponding management message, a‘Number of stations’ field indicating unique numbers of MSs, a ‘Powermanagement frame’ field indicating a power management frame, a ‘BasicCID’ field indicating a basic Connection Identifier (CID) for each ofMSs, and a ‘Power adjust’ field indicating power adjustment for each ofthe MSs. To transmit power control information of the MSs through theFPC message, the BS includes basic CIDs of the MSs in the Basic CIDfield of the FPC message and transmits the FPC message to the MSs.

An IEEE 802.16 communication system, a typical BWA communication system,has a frame structure, and a BS of the system efficiently allocatesresources of each frame to MSs, and transmits the resource allocationinformation to the MSs through a MAP message. A MAP message used fortransmitting the downlink resource allocation information is a DL-MAPmessage, and a MAP message used for transmitting uplink resourceallocation information is a UL-MAP message.

When the BS transmits the downlink resource allocation information andthe uplink resource allocation information through the DL-MAP messageand the UL-MAP message in this manner, the MSs can decode the DL-MAPmessage and the UL-MAP message, transmitted from the BS, and detecttherefrom power control information, and control information for theallocation locations where resources are allocated to them, and for thedata that they should receive. The MSs can receive or transmit data overthe downlink or the uplink by detecting the resource allocation locationand control information. In addition, when transmitting data, the MSscan control transmission power using the power control information.

The MAP message is composed of different MAP IE formats according towhether it is for a downlink or an uplink, and according to a type of adata burst, i.e. according to whether the data burst is (i) a data burstto which Hybrid Automatic Repeat reQuest (HARQ) is applied (HARQ databurst), (ii) a data burst to which HARQ is not applied (Non-HARQ databurst), or (iii) control information. Therefore, the MSs shouldpreviously know a format of each MAP IE to decode the MAP IE, and eachMAP IE can be distinguished using a Downlink Interval Usage Code (DIUC),for the downlink, and using an Uplink Interval Usage Code (UIUC), forthe uplink.

As described above, in the BWA communication system, data transmissionis performed frame by frame, and each frame is divided into a field fortransmitting downlink data and a field for transmitting uplink data. Thefields for transmitting data are formed in a 2-dimensional arrangementof ‘frequency domain’×‘time domain’, and each element in the2-dimensional arrangement is a slot which is an allocation unit. Thatis, the frequency domain is divided in units of subchannels, each ofwhich is a bundle of subcarriers, and the time domain is divided inunits of symbols. Therefore, the slot indicates a field where a symbolis occupied by one subchannel. Each slot is allocated only to onearbitrary MS among the MSs located in one cell, and a set of slotsallocated to each of MSs located in the cell is a burst. As describedabove, in the communication system, uplink wireless resources areallocated in such a manner that slots are shared by MSs. With referenceto FIG. 1, a description will now be made of a frame structure in acommunication system according to the present invention.

FIG. 1 shows a frame structure in a communication system according tothe present invention. Referring to FIG. 1, the frame is shown bysubchannels in the frequency domain and symbols in the time domain. They-axis indicates subchannels which are resource units of frequency, andthe x-axis indicates OFDM symbols which are resource units of time. Theframe includes a preamble field 102, a DL-MAP message field 104, aUL-MAP message field 106, a downlink burst (DL Burst) field 108, and anuplink burst (UL Burst) field 110.

The preamble field 102 is used for transmitting a synchronizationsignal, or a preamble sequence, for acquisition of atransmission/reception period, i.e. acquisition of synchronizationbetween a BS and MSs in a communication system. The DL-MAP message field104 is used for transmitting a DL-MAP message, and the UL-MAP messagefield 106 is used for transmitting a UL-MAP message. The DL-MAP messagefield 104, although not shown, includes a plurality of IEs, and the IEseach include information on the corresponding downlink burst field.Similarly, the UL-MAP message field 106, although not shown, includes aplurality of IEs, and the IEs each include information on thecorresponding uplink burst field and power control information of theMSs. The downlink burst field 108 is used for transmitting thecorresponding downlink data burst, and the uplink burst field 110 isused for transmitting the corresponding uplink data burst. Withreference to FIG. 2 and Table 2, a description will now be made of ascheme of transmitting power control IEs in UL-MAP IEs of a UL-MAPmessage, among the above-described schemes of transmitting power controlinformation in a message.

FIG. 2 shows a structure of a UL-MAP message field of a frame in acommunication system according to the present invention. Referring toFIG. 2, the UL-MAP message field 201 includes a UL-MAP basic informationfield 203 for transmitting basic information of a UL-MAP message, and aper-burst UL-MAP IE field 205 for transmitting per-burst UL-MAP IEs. Theper-burst UL-MAP IE field 205 includes a CID/UIUC field 207 fortransmitting CID and UIUC for per-burst allocation information and powercontrol information of the MSs, an allocation information field 209 fortransmitting burst allocation information, and an extendedUIUC-dependent IE field 211 for transmitting extended UIUC-dependentIEs, and the extended UIUC-dependent IE field 211 includes a powercontrol IE field 213 for transmitting power control IEs having powercontrol parameters separately defined for individual MSs, fortransmitting power control information of the MSs.

Table 2 shows UL-MAP IEs of a UL-MAP message, which include powercontrol IEs.

TABLE 2 Syntax Bits UL-MAP_IE{  CID 16 bits   UIUC 4 bits  if(UIUC==15){  Extended_(—) UIUC_dependent_IE{    Power_Control_IE{     Extended_(—)UIUC=0x00 4 bits     Length 4 bits     Power_Control 8 bits    }   }  }}

As shown in Table 2, UL-MAP IEs of the UL-MAP message include CID andUIUC for per-burst allocation information and power control informationof the MSs, and extended UIUC-dependent IEs, and the extendedUIUC-dependent IEs include power control IEs having power controlparameters separately defined for individual MSs according to powercontrol information of the MSs. With reference to Table 3, a descriptionwill now be made of a scheme of transmitting Fast Tracking IEs in UL-MAPIEs of a UL-MAP message, among the above-described schemes oftransmitting power control information in a message.

Table 3 shows UL-MAP IEs of a UL-MAP message, which include FastTracking IEs.

TABLE 3 Syntax Bits UL-MAP_IE{  CID 16 bits   UIUC 4 bits  if(UIUC==15){  Extended_(—) UIUC_dependent_IE{     UL-MAP_Fast_Tracking_IE{     Extended_(—) UIUC=0x07 4 bits      Length variable      Map Index 2bits      for(i=0;i<n;1++){       Power correction 3 bits      Frequency correction 3 bits       Time correction 2 bits        }   }   }  } }

As shown in Table 3, UL-MAP IEs of the UL-MAP message, like in Table 2,include CID and UIUC for per-burst allocation information and powercontrol information of the MSs, and extended UIUC-dependent IEs. Whilethe extended UIUC-dependent IEs of the UL-MAP IEs of the UL-MAP message,shown in Table 2, include the power control IEs having power controlparameters separately defined for individual MSs depending on the powercontrol information of the MSs, the extended UIUC-dependent IEs of theUL-MAP IEs of the UL-MAP message, shown in Table 3, include FastTracking IEs of the UL-MAP message, which include power controlinformation for all MSs located in the cell. The Fast Tracking IEs ofthe UL-MAP message are used as additional information in addition to theinformation for the MSs, previously delivered at a previous frame, andare equal to unicast allocation IEs in the UL-MAP message. In addition,the Fast Tracking IEs of the UL-MAP message can be transmitted over thepower control IE field 213 of FIG. 2, over which the power control IEsshown in Table 2 are transmitted.

A description will now be made of a scheme in which a BS transmits in aforegoing message a power control bit sequence of power controlinformation generated according to CQIs of MSs in a communication systemaccording to the present invention. A description will then be made of aprocess of transmitting the message including the power control bitsequence to the MSs, and controlling power of the MSs. With reference toFIG. 3, a description will first be made of a burst allocationinformation field and power control information field in the MAP messagefield of the foregoing frame. With reference to FIG. 4, a descriptionwill be made of the power control bit sequence of the power controlinformation that the BS has generated depending on CQIs of the MSs.Thereafter, with reference to FIG. 5, a description will be made ofCQICH allocation for transmission of CQIs of the MSs, and with referenceto FIGS. 6 and 7, a description will be made of a method of mapping thegenerated power control information to the corresponding MSs accordingto the CQICH allocation information.

FIG. 3 shows a burst allocation information field and a power controlinformation field in a MAP message field of a frame in a communicationsystem according to the present invention. Referring to FIG. 3, in thecommunication system, when N MSs are located in a cell, a burst field ofthe frame is divided into N sub-burst fields, and then allocated to theN MSs on a one-to-one basis. The allocation information of the dividedburst field is transmitted to the MSs over a MAP message field of theframe, which is divided into N burst allocation information fields310-1, 310-2, . . . , 310-N. At this point, power control information ofthe MSs is transmitted to the MSs over one power control informationfield 320 divided from the MAP message field. That is, in acommunication system according to the present invention, power controlinformation of all MSs located in a particular cell is transmitted tothe MSs, i.e. broadcasted to the MSs, over the one power controlinformation field 320 allocated in the MAP message field of the frame.Accordingly, in a communication system according to the presentinvention, even though a number of MSs located in a particular cellincreases, the system can minimize an increase in overhead as a BS incharge of the cell transmits per-frame power control information of theMSs over the one power control information field 320 allocated in theMAP message field of the frame. In addition, a communication systemaccording to the present invention can rapidly control power of the MSsas the BS transmits per-frame power control information of the MSs overthe one power control information field 320 allocated in the MAP messagefield of the frame.

FIG. 4 shows a power control bit sequence for power control in acommunication system according to the present invention. Referring toFIG. 4, in the communication system, a BS generates power controlinformation of MSs according to CQIs received from N MSs located in thecell of the BS, and generates a power control bit sequence of the MSs,i.e. N power control bits 410-1, 410-2, . . . , 410-N for the MSs,according to the generated power control information. The power controlbits 410-1, 410-2, . . . , 410-N of the MSs are each composed of m bits.

More specifically, for m=1, indicating that the power control bits410-1, 410-2, . . . , 410-N of the MSs are each composed of 1 bit, whenthe power control bits 410-1, 410-2, . . . , 410-N of the MSs are set to‘0’, the MSs are ordered to keep the current power level, and when thepower control bits 410-1, 410-2, . . . , 410-N of the MSs are set to‘1’, the MSs are ordered to increase or decrease the current power levelby a threshold. For m=2, indicating that the power control bits 410-1,410-2, . . . , 410-N of the MSs are each composed of 2 bits, when thepower control bits 410-1, 410-2, . . . , 410-N of the MSs are set to‘00’, the MSs are ordered to keep the current power level; when thepower control bits 410-1, 410-2, . . . , 410-N of the MSs are set to‘01’, the MSs are ordered to increase the current power level by athreshold; and when the power control bits 410-1, 410-2, . . . , 410-Nof the MSs are set to ‘11’, the MSs are ordered to decrease the currentpower level by a threshold. For m=n, indicating that the power controlbits 410-1, 410-2, . . . , 410-N of the MSs are each composed of n bits,power of the MSs is changed in a type of a signed integer. For example,for n=5, when the power control bits 410-1, 410-2, . . . , 410-N of theMSs are set to ‘00100’, the MSs are ordered to increase the currentpower level by 4 times a threshold, and when the power control bits410-1, 410-2, . . . , 410-N of the MSs are set to ‘11100’, the MSs areordered to decrease the current power level by 4 times a threshold.Current power level, as used herein, refers to a transmission powerlevel used when the MSs transmit their CQIs to the BS over CQICHs, andthe ‘threshold’ refers to a value predetermined by the user or thesystem according to communication system and communication environment.

FIG. 5 shows allocation of CQICHs over which a BS receives CQIs from MSsin a communication system according to the present invention. Referringto FIG. 5, the BS of the communication system includes, in an (n−k)^(th)frame 501, a preamble field 551, a DL-MAP message field 553, a UL-MAPmessage field 555, a downlink burst field 557, and an uplink burst field559, as described in FIG. 1. The BS transmits to MSs a UL-MAP messagewhich is transmitted over the UL-MAP message field 555 of the (n−k)^(th)frame 501, and allocates it to a downlink burst field 571 of an n^(th)frame 503 to provide the MSs with information on a CQI field 573indicating CQIs to be transmitted by the MSs, and information on a CQICHfield 577 allocated such that the MSs may transmit CQIs over itaccording to information transmitted over the CQI field 573. That is,the BS broadcasts to the MSs the UL-MAP message transmitted over theUL-MAP message field 555 of the (n−k)^(th) frame 501, so the MSs canacquire information on the CQICH field 577 allocated to the MSsthemselves in an uplink burst field 575 of the n^(th) frame 503 andinformation on CQIs transmitted over the allocated CQICH field 577. Withreference to FIGS. 6A and 7A, a detailed description will now be made ofCQICH allocation to the MSs, and with reference to FIGS. 6B and 7B, adescription will be made of mapping of power control information to thecorresponding MSs according to the CQICH allocation of FIGS. 6A and 7A.

FIGS. 6A and 6B show a method of mapping power control information tocorresponding MSs according to CQICH allocation information of the MSsin a communication system according to the present invention. Referringto FIGS. 6A and 6B, in the communication system, when there are N MSslocated in a cell, a CQICH field in an uplink burst field of a frame isdivided into N sub-CQICH fields 610-1, 610-2, 610-3, . . . , 610-(N−1),610-N, and then allocated to the N MSs on a one-to-one basis. Theallocation information of the divided CQICH field is broadcasted to theN MSs over a MAP message field, i.e. the UL-MAP message field, of theframe as described above. The sub-CQICH fields 610-1, 610-2, 610-3, . .. , 610-(N−1), 610-N are allocated to the MSs at every frame so the MSsmay transmit CQIs to the BS over them. As described above, based on theMAP message, the MSs each recognize CQICHs allocated to them by the BS,in other words, recognize indexes CQI #1, CQI #2, CQI #3, . . . , #CQI#(N−1) and CQI #N of CQICHs, for example, unique numbers and allocationorders of CQICHs allocated to them at every frame by the BS.

For convenience, it will be assumed herein that the BS allocates asub-CQICH field 610-1 with a CQICH index=CQI #1 to a first MS among theN MSs, allocates a sub-CQICH field 610-2 with a CQICH index=CQI #2 to athird MS, allocates a sub-CQICH field 610-3 with a CQICH index=CQI #3 toa second MS, allocates a sub-CQICH field 610-(N−1) with a CQICHindex=CQI #(N−1) to an N^(th) MS, and allocates a sub-CQICH field 610-Nwith a CQICH index=CQI #N to an (N−1)^(th) MS. Then the MSs, becausethey already know indexes of CQICHs allocated to them from the MAPmessage as described above, transmit their CQIs to the BS over sub-CQICHfields corresponding to the recognized CQICH indexes.

Upon receipt of CQIs from the MSs over CQICHs, the BS generates powercontrol information of the MSs and generates a power control bitsequence according to the generated power control information asdescribed above, and then maps the generated power control informationfor the MSs to the corresponding MSs according to the CQICH allocationinformation of the MSs. That is, when all CQICH channels are allocatedto all of N MSs, as shown in FIG. 6A, the BS maps the power controlinformation for the MSs to the corresponding MSs in a message, forexample, a MAP message field, i.e. DL-MAP message field or UL-MAPmessage field, of a frame, according to the CQICH allocation informationof the MSs, as shown in FIG. 6B.

That is, as the BS generates power control information according to theCQIs after allocating CQICHs to all of N MS and receiving the CQIs overthe allocated CQICHs as described above, one power control informationfield allocated for transmitting power control information for the MSsis divided into N sub-fields 660-1, 660-2, 660-3, . . . , 660-(N−1) and660-N, where N is the number of MSs, as described in FIG. 3, and thenmapped to the N MSs, i.e. allocated to the N MSs on a one-to-one basis.The N sub-fields 660-1, 660-2, 660-3, . . . , 660-(N−1) and 660-N aremapped according to the CQICH allocation information of the MSs, forexample, indexes of CQICHs allocated to the MSs.

Under the foregoing assumption given for convenience, a first sub-field660-1 among the N sub-fields 660-1, 660-2, 660-3, . . . , 660-(N−1) and660-N is mapped, or allocated, to the first MS to which the sub-CQICHfield 610-1 with a CQICH index=CQI #1 is allocated; a second sub-field660-2 is mapped, or allocated, to the third MS to which the sub-CQICHfield 610-2 with a CQICH index=CQI #2 is allocated; a third sub-field660-3 is mapped, or allocated, to the second MS to which the sub-CQICHfield 610-3 with a CQICH index=CQI #3 is allocated; an (N−1)^(th)sub-field 660-(N−1) is mapped, or allocated, to the N^(th) MS to whichthe sub-CQICH field 610-(N−1) with a CQICH index=CQI #(N−1) isallocated; and an N′h sub-field 660-N is mapped, or allocated, to the(N−1)^(th) MS to which the sub-CQICH field 610-N with a CQICH index=CQI#N is allocated. The power control information is transmitted to theMSs, i.e. broadcasted to N MSs located in the cell, over the sub-fields660-1, 660-2, 660-3, . . . , 660-(N−1) and 660-N, which are allocated tothe MSs according to the CQICH allocation information of the MSs. Then,the MSs each recognize, from the CQICH allocation information includedin the MAP message field, a sub-field over which power controlinformation associated with each MS is transmitted, the sub-field beingallocated in the one power control information field, detect powercontrol information transmitted over the sub-field, and control powerfor the associated MS depending on the detected power controlinformation.

FIGS. 7A and 7B show a method of mapping power control information tocorresponding MSs according to CQICH allocation information of MSs in acommunication system according to the present invention. A descriptionof FIGS. 7A and 7B is given herein for a case where no CQICH isallocated to the third MS and the (N−1)^(th) MS in FIGS. 6A and 6B, andthus, the third MS and the (N−1)^(th) MS do not transmit their CQIs tothe BS.

Referring to FIGS. 7A and 7B, in a communication system, when there areN MSs located in a cell, a CQICH field in an uplink burst field of aframe is divided into N sub-CQICH fields 710-1, 710-2, 710-3, . . . ,710-(N−1) and 710-N, and then allocated to the N MSs on a one-to-onebasis. The allocation information of the divided CQICH field isbroadcast to the N MSs over a MAP message field, i.e. UL-MAP messagefield, of the frame, as described above. In addition, the sub-CQICHfields 710-1, 710-2, 710-3, . . . , 710-(N−1) and 710-N are allocated tothe MSs at every frame so that the MSs may transmit CQIs to the BS. Asdescribed above, based on the MAP message, the MSs each recognize CQICHsallocated to them by the BS, in other words, recognize indexes CQI #1,CQI #2, CQI #3, . . . , #CQI #(N−1) and CQI #N of CQICHs, for example,unique numbers and allocation orders of CQICHs allocated to them atevery frame by the BS.

Under the foregoing assumption that the BS allocates no CQICH to thethird MS and the (N−1)^(th) MS among the N MSs, because the BS allocatesa sub-CQICH field 710-1 with a CQICH index=CQI #1 to a first MS amongthe N MSs and allocates no CQICH to the third MS, a sub-CQICH field710-2 with a CQICH index=CQI #2 is not allocated, and because the BSallocates a sub-CQICH field 710-3 with a CQICH index=CQI #3 to a secondMS, allocates a sub-CQICH field 710-(N−1) with a CQICH index=CQI #(N−1)to an N^(th) MS, and allocates no CQICH to an (N−1)^(th) MS, a sub-CQICHfield 710-N with a CQICH index=CQI #N is not allocated. Then, the MSs,because they already know indexes of CQICHs allocated to them from theMAP message as described above, transmit their CQIs to the BS oversub-CQICH fields corresponding to the recognized CQICH indexes. That is,while the BS in FIG. 6A allocates CQICHs so all of N MSs may transmittheir CQIs to the BS, i.e. allocates the N sub-fields 660-1, 660-2,660-3, . . . , 660-(N−1) and 660-N to all of N MSs, respectively, the BSin FIG. 7A allocates no CQICH to the third MS and the (N−1)^(th) MSamong the N MSs so they do not transmit their CQIs to the BS, and thus,the sub-CQICH fields 710-2 and 710-N with CQICH index=CQI #2 and CQI #Nare not allocated to the MSs.

Upon receipt of CQIs over CQICHs from the MSs except for the third MSand the (N−1)^(th) MS among the N MSs, the BS generates power controlinformation of the MSs and generates a power control bit sequenceaccording to the generated power control information as described above,and then maps the generated power control information of the MSs to thecorresponding MSs according to the CQICH allocation information of theMSs. That is, when CQICH channels are allocated to the remaining MSsexcept for the third MS and the (N−1)^(th) MS among the N MSs, as shownin FIG. 7A, the BS maps the power control information for the MSs to thecorresponding MSs in a message, for example, a MAP message field, i.e.DL-MAP message field or UL-MAP message field, of a frame, according tothe CQICH allocation information of the MSs, as shown in FIG. 7B.

That is, as the BS generates power control information according to theCQIs after allocating CQICHs to the remaining MSs except for the thirdMS and the (N−1)^(th) MS among the N MS and receiving the CQIs over theallocated CQICHs as described above, one power control information fieldallocated for transmitting power control information for the MSs isdivided into N sub-fields 760-1, 760-2, 760-3, . . . , 760-(N−1) and760-N, where N is the number of MSs, as described in FIG. 3, and thenmapped, i.e. allocated, to the remaining MSs except for the third MS andthe (N−1)^(th) MS among the N MSs, respectively. The N sub-fields 760-1,760-2, 760-3, . . . , 760-(N−1) and 760-N are mapped according to theCQICH allocation information of the MSs, for example, indexes of CQICHsallocated to the MSs.

Under the foregoing assumption given for convenience, a first sub-field760-1 among the N sub-fields 760-1, 760-2, 760-3, . . . , 760-(N−1) and760-N is mapped, or allocated, to the first MS to which the sub-CQICHfield 710-1 with a CQICH index=CQI #1 is allocated; a second sub-field760-2 is not mapped, or not allocated, to any MS as the sub-CQICH field710-2 with a CQICH index=CQI #2 is not allocated; a third sub-field760-3 is mapped, or allocated, to the second MS to which the sub-CQICHfield 710-3 with a CQICH index=CQI #3 is allocated; an (N−1)^(th)sub-field 760-(N−1) is mapped, or allocated, to the N^(th) MS to whichthe sub-CQICH field 710-(N−1) with a CQICH index=CQI #(N−1) isallocated; and an N^(th) sub-field 760-N is not mapped, or notallocated, to any MS as the sub-CQICH field 710-N with a CQICH index=CQI#N is not allocated. The power control information is transmitted to theMSs, i.e. broadcasted to N MSs located in the cell, over the sub-fields760-1, 760-3, . . . , 760-(N−1), which are allocated to the MSsaccording to the CQICH allocation information of the MSs. Then, the MSseach recognize, from the CQICH allocation information included in theMAP message field, a sub-field over which its power control informationis transmitted, the sub-field being allocated in the one power controlinformation field, detect power control information transmitted over thesub-field, and control power associated with each MS depending on thedetected power control information. Of the second sub-field 760-2 andthe N^(th) sub-field 760-N not allocated to the MSs, the N^(th)sub-field 760-N can be allocated for transmission of data other thantransmission of power control information, thereby contributing to areduction in length of a power control burst and to efficient use ofresources. A description will now be made of a scheme in which a BStransmits in a message the power control bit sequence of the powercontrol information generated according to CQIs received from MSs in thecommunication system according to the present invention.

Table 4 shows a format of a MAP message when the BS generates a powercontrol bit sequence of power control information generated according toCQIs received from MSs and transmits the power control bit sequence inthe MAP message, for example, DL-MAP message or UL-MAP message, in thecommunication system according to the present invention.

TABLE 4 Syntax Bits MAP Message{  ...  Power_Control_Broadcasting{   Length x-bits    Power_Control_Bit_Sequence variable  } }

As shown in Table 4, the MAP message includes aPower_Control_Broadcasting field, and the Power_Control_Broadcastingfield includes a ‘Length’ field indicating a length of thePower_Control_Broadcasting field, and a Power_Control_Bit_Sequence fieldindicating a power control bit sequence generated according to powercontrol information of the MSs. The power control bit sequence has beendescribed with reference to FIG. 4, and length information of the powercontrol bit sequence is transmitted to the MSs over a Downlink ChannelDescriptor (DCD) or an Uplink Channel Descriptor (UCD). The DCD and theUCD are messages periodically transmitted with defined physical channelcharacteristics of the downlink and the uplink, respectively, and theseare not directly related to the present invention, so associateddescriptions are omitted. The BS broadcasts in the MAP message to theMSs a power control bit sequence with power control informationgenerated according to CQIs received over CQICHs from the MSs.

Table 5 shows MAP IEs when the BS transmits in DL-MAP IEs or UL-MAP IEsof a MAP message, for example, DL-MAP message or UL-MAP message, a powercontrol bit sequence of power control information generated according toCQIs received from the MSs in the communication system according to thepresent invention.

TABLE 5 Syntax Bits DL(or UL)-MAP_IE{  CID=FFFF(Broadcasting CID) 16bits   DIUC(or UIUC) 4 bits  Extended-DIUC(or(UIUC)_dependent_IE{  Power_Control_Broadcast_IE{     Extended_(—) DIUC(or UIUC) 4 bits    Length x-bits     Power_Control_Bit_Sequence variable   }  } }

As shown in Table 5, the DL-MAP IEs or UL-MAP IEs of the DL-MAP messageor UL-MAP message include CID and UIUC or DIUC for per-burst allocationinformation and power control information of the MSs, and extendedUIUC-dependent IEs or extended DIUC-dependent IEs. The extendedUIUC-dependent IEs or extended DIUC-dependent IEs include the powercontrol bit sequence. With reference to Table 6, a description will nowbe made of a method in which the BS transmits, in a power controlmessage in a type of a MAC message other than the MAP message, the powercontrol bit sequence of power control information generated according toCQIs received from the MSs in the communication system according to thepresent invention.

Table 6 shows a format of a power control message when a BS transmits ina power control message a power control bit sequence of power controlinformation generated according to CQIs received from MSs in acommunication system according to the present invention.

TABLE 6 Syntax Bits Power_Control_Message{  Management Message Type 8bits   Length x-bits  Power_Control_Bit_Sequence variable }

As shown in Table 6, the power control message includes a ‘ManagementMessage Type’ field indicating a type of the corresponding managementmessage, a ‘Length’ field indicting a length of the MAC message, and aPower_Control_Bit_Sequence field indicating a power control bit sequencegenerated according to power control information of the MSs. Withreference to FIG. 8, a description will now be made of an operation inwhich a BS controls power of MSs in a communication system according tothe present invention.

FIG. 8 shows an operation in which a BS controls power of MSs in acommunication system according to the present invention. Referring toFIG. 8, in step 801, the BS receives CQIs of MSs over CQICHs previouslyallocated to receive CQIs from the MSs located in the cell of the BS,and generates power control information of the MSs according to thereceived CQIs. Thereafter, in step 803, the BS generates a power controlbit sequence according to the generated power control information asdescribed with reference to FIG. 4. An operation of generating the powercontrol bit sequence has been described in FIG. 4.

Next, in step 805, the BS allocates CQICHs to the MSs so the MSs maytransmit their CQI information as described above, and maps the powercontrol information to the corresponding MSs according to the CQICHallocation information. That is, the BS divides one power controlinformation field previously allocated for transmission of the powercontrol information generated in step 801, according to the number ofthe MSs, and then allocates the divided power control information fieldsto the MSs according to the CQICH allocation information, therebymapping the power control information to the corresponding MSs. Anoperation of mapping the power control information to the MSs accordingto the CQICH allocation information has been described with reference toFIGS. 6 and 7.

In step 807, the BS includes the power control bit sequence generated instep 803 in a message, and then transmits, or broadcasts, the messageincluding the power control bit sequence to the MSs located in the cell.The message including the power control bit sequence of the generatedpower control information is a power control message in a type of a MACmessage, or a MAP message, and is broadcast to the MSs. With referenceto FIG. 9, a description will now be made of an operation of controllingpower by an MS in a communication system according to the presentinvention.

FIG. 9 shows an operation of controlling power by an MS in acommunication system according to the present invention. Referring toFIG. 9, in step 901, the MS transmits a CQI of the MS to a BS of the MSover a CQICH allocated by the BS, and upon receipt of a message from theBS, detects a power control bit sequence included in the message. Basedon information included in the message received from the BS, the MSrecognizes a field where the power control bit sequence is transmitted.An operation of generating, by the BS, power control information of theMS according to the CQI and transmitting the message including the powercontrol information has been previously described. In addition, anoperation of recognizing, by the MS, the field where the power controlbit sequence is transmitted, based on the information included in themessage received from the BS, is equal to the operation of recognizingone power control information field based on the MAP message, so adescription thereof will be omitted.

Thereafter, in step 903, the MS detects power control informationcorresponding thereto from the power control information transmittedover the power control information field according to the CQICHallocation information included in the message. That is, because the BSmaps the power control information to the corresponding MSs according tothe CQICH allocation information before transmission as described above,the MS detects power control information of the MS according to themapping. An operation of detecting the power control information by theMS has been described above. Next, in step 905, the MS controlstransmission power of the MS, i.e. power of a transmission signal to theBS, according to the power control information detected in step 903.

FIGS. 10A and 10B show a power controller of a BS in a communicationsystem according to the present invention. The power controller shown inFIG. 10A is for a case where a BS transmits a power control bit sequencein a MAP message, and the power controller shown in FIG. 10B is for acase where a BS transmits a power control bit sequence in a MAC message,i.e. power control message.

Referring to FIG. 10A, the power controller of the BS includes a CQICHallocator 1001 for allocating CQICHs to receive CQIs from MSs located inthe cell of the BS, a power control information generator 1003 forreceiving CQIs of the MSs over the CQICHs allocated by the CQICHallocator 1001 and generating power control information of the MSsaccording to the received CQIs, a power control bit sequence generator1005 for generating a power control bit sequence according to the powercontrol information generated by the power control information generator1003 as described with reference to FIG. 4, and a MAP message generator1007 for generating a MAP message including the CQICH allocationinformation of MSs, allocated by the CQICH allocator 1001, and the powercontrol bit sequence generated by the power control bit sequencegenerator 1005, and then broadcasting the generated MAP message to theMSs. The power control bit sequence generator 1005 maps the powercontrol information of the MSs, received from the power controlinformation generator 1003, to the corresponding MSs according to theCQICH allocation information of the MSs, allocated by the CQICHallocator 1001, and then transmits the generated power control bitsequence to the MAP message generator 1007. This power control operationof the BS has been described above.

Referring to FIG. 10B, the power controller of the BS of FIG. 10B issimilar to the power controller of the BS of FIG. 10A, except that thepower controller of FIG. 10A includes a MAP message generator 1007 fortransmitting the power control bit sequence in a MAP message, whereasthe power controller of FIG. 10B includes a MAC message generator 1057for transmitting a power control bit sequence in a MAC message.

More specifically, the power controller of the BS of FIG. 10B includes aCQICH allocator 1051 for allocating CQICHs to receive CQIs from MSslocated in the cell of the BS, a power control information generator1053 for receiving CQIs of the MSs over the CQICHs allocated by theCQICH allocator 1051 and generating power control information of the MSsaccording to the received CQIs, a power control bit sequence generator1055 for generating a power control bit sequence according to the powercontrol information generated by the power control information generator1053 as described with reference to FIG. 4, and a MAC message generator1057 for generating a MAC message including the CQICH allocationinformation of the MSs, allocated by the CQICH allocator 1051, and thepower control bit sequence generated by the power control bit sequencegenerator 1055, and then broadcasting the generated MAC message to theMSs. The power control bit sequence generator 1055 maps the powercontrol information of the MSs, received from the power controlinformation generator 1053, to the corresponding MSs according to theCQICH allocation information of the MSs, allocated by the CQICHallocator 1051, and then transmits the generated power control bitsequence to the MAC message generator 1057. This power control operationof the BS has been described above.

FIG. 11 shows a power controller of an MS in a communication systemaccording to the present invention. Referring to FIG. 11, the powercontroller of the MS includes a CQICH allocation decider 1101 for, uponreceipt of a message from a BS, determining whether a CQICH of the MS isallocated depending on CQICH allocation information included in themessage, and detecting CQICH allocation information from the messagewhen it is determined that the CQICH of the MS is allocated, a powercontrol bit sequence detector 1103 for detecting a power control bitsequence included in the message, a power control information detector1105 for detecting power control information corresponding to the MSitself from the power control bit sequence detected by the power controlbit sequence detector 1103 according to the CQICH allocation informationdetected by the CQICH allocation decider 1101, and a power controller1107 for controlling transmission power to the BS according to the powercontrol information detected by the power control information detector1105. The power control bit sequence detector 1103 recognizes a fieldwhere the power control bit sequence is transmitted, depending on theinformation included in the message received from the BS, and becausethe BS maps the power control information to the corresponding MSsaccording to the CQICH allocation information before transmission, thepower control information detector 1105 detects power controlinformation according to the mapping. This power control operation ofthe MS has been described before.

As is apparent from the foregoing description, according to the presentinvention, a BS generates power control information according to channelinformation received from MSs located in a cell of the BS, andbroadcasts, to the MSs, generated power control information of the MSsaccording to allocation information of channels allocated to receive thechannel information. As a result, even though a number of MSs located inthe cell increases, the BS can transmit per-frame power controlinformation of the MSs over one burst field, thereby minimizing anincrease in the overhead and facilitating fast power control of the MSs.

While the invention has been shown and described with reference tocertain preferred embodiments thereof, it will be understood by thoseskilled in the art that various changes in form and details may be madetherein without departing from the spirit and scope of the invention asdefined by the appended claims.

1. A method for controlling power at a base station in a communicationsystem, the method comprising: receiving channel information from aplurality of mobile stations, and generating power control informationof the mobile stations according to the received channel information;mapping the generated power control information to transmission fieldsof corresponding mobile stations according to allocation information ofchannels allocated to receive the channel information; and broadcastingto the mobile stations a message including the power control informationmapped to the transmission fields of the corresponding mobile stations.2. The method of claim 1, wherein the mapping comprises: dividing atransmission field of the power control information into a plurality ofsub-fields according to allocation information of channels allocated toreceive the channel information, and then allocating the sub-fields tothe corresponding mobile stations.
 3. The method of claim 2, wherein theallocating comprises: determining a field for transmitting power controlinformation of the corresponding mobile stations among the sub-fieldsaccording to the allocation information of the channels allocated toreceive the channel information.
 4. The method of claim 2, wherein thedividing comprises: dividing one transmission field into as manysub-fields as a number of the mobile stations.
 5. The method of claim 2,wherein the allocation information comprises indexes including uniquenumbers and allocation orders of the allocated channels.
 6. The methodof claim 2, wherein the allocating comprises: allocating the sub-fieldsaccording to unique numbers and allocation orders of the allocatedchannels.
 7. The method of claim 1, wherein the message is a MAP messageincluding a power control bit sequence generated according to the powercontrol information.
 8. The method of claim 7, wherein the power controlbit sequence comprises power control bits for the mobile stationsaccording to the power control information of the mobile stations. 9.The method of claim 8, wherein the power control bits for the mobilestations comprise a change in a power level by a threshold from atransmission power level used when the mobile stations transmit channelinformation to the base station.
 10. The method of claim 1, wherein themessage is a Medium Access Control (MAC) message including a powercontrol bit sequence generated according to the power controlinformation.
 11. The method of claim 10, wherein the power control bitsequence comprises power control bits for the mobile stations accordingto the power control information of the mobile stations.
 12. The methodof claim 11, wherein the power control bits for the mobile stationscomprise a change in a power level by a threshold from a transmissionpower level used when the mobile stations transmit channel informationto the base station.
 13. The method of claim 1, wherein the messagecomprises allocation information of channels allocated to receive thechannel information.
 14. A method for controlling power at a mobilestation in a communication system, the method comprising: receiving amessage including power control information from a base station, anddetecting power control information included in the message; anddetecting power control information corresponding to the base stationfrom the detected power control information according to allocationinformation of a channel allocated to transmit channel information ofthe mobile station to the base station.
 15. The method of claim 14,wherein the allocation information comprises an index including a uniquenumber and allocation order of the allocated channel.
 16. The method ofclaim 14, wherein the detecting power control information correspondingto the base station comprises: checking a sub-field corresponding to themobile station according to allocation information of the allocatedchannel among a plurality of sub-fields allocated to transmit powercontrol information of other mobile stations including the mobilestation, and detecting power control information transmitted over thechecked sub-field.
 17. The method of claim 16, wherein the checkingcomprises: checking a sub-field corresponding to the mobile stationaccording to a unique number and allocation order of the allocatedchannel.
 18. The method of claim 14, wherein the message is a MAPmessage including a power control bit sequence generated according tothe power control information.
 19. The method of claim 18, wherein thepower control bit sequence comprises a power control bit for the mobilestation according to the power control information of the mobilestation.
 20. The method of claim 19, wherein the power control bit forthe mobile station comprises a change in a power level by a thresholdfrom a transmission power level used when the mobile station transmitschannel information to the base station.
 21. The method of claim 14,wherein the message is a Medium Access Control (MAC) message including apower control bit sequence generated according to the power controlinformation.
 22. The method of claim 21, wherein the power control bitsequence comprises a power control bit for the mobile station accordingto the power control information of the mobile station.
 23. The methodof claim 22, wherein the power control bit for the mobile stationcomprises a change in a power level by a threshold from a transmissionpower level used when the mobile station transmits channel informationto the base station.
 24. The method of claim 14, wherein the messagecomprises allocation information of a channel allocated to receive thechannel information.
 25. A method for transmitting control informationfor at least one mobile station at base station in a communicationsystem, the method comprising: receiving channel information from atleast one mobile station; generating control information of mobilestations according to the received channel information; mapping thegenerated control information to transmission fields of correspondingmobile stations according to allocation orders of channels for the atleast one mobile station, allocated to receive the channel information;and broadcasting, to the mobile stations, a message includingtransmission fields to which the control information of thecorresponding mobile stations is mapped.
 26. The method of claim 25,wherein the control information comprises power control information ofthe mobile stations.
 27. The method of claim 25, wherein the mappingcomprises: mapping the control information without connectionidentifiers for the mobile stations.
 28. A system for controlling powerin a communication system, the system comprising: a base station forreceiving channel information from a plurality of mobile stations,generating power control information of the mobile stations according tothe received channel information, mapping the generated power controlinformation to transmission fields of corresponding mobile stationsaccording to allocation information of channels allocated to receive thechannel information, and broadcasting to the mobile stations a messageincluding the power control information mapped to the transmissionfields of the corresponding mobile stations.
 29. The system of claim 28,wherein the base station divides a transmission field of the powercontrol information into a plurality of sub-fields according toallocation information of channels allocated to receive the channelinformation, allocates the sub-fields to the corresponding mobilestations, and maps the generated power control information to thetransmission fields of the corresponding mobile stations.
 30. The systemof claim 29, wherein the base station determines a field fortransmitting power control information of the corresponding mobilestations among the sub-fields according to the allocation information ofthe channels allocated to receive the channel information, and allocatesthe sub-fields to the corresponding mobile stations.
 31. The system ofclaim 29, wherein the base station divides one transmission field intoas many sub-fields as a number of the mobile stations.
 32. The system ofclaim 29, wherein the allocation information comprises indexes includingunique numbers and allocation orders of the allocated channels.
 33. Thesystem of claim 29, wherein the base station allocates the sub-fields tothe corresponding mobile stations according to unique numbers andallocation orders of the allocated channels.
 34. The system of claim 28,wherein the message is a MAP message including a power control bitsequence generated according to the power control information.
 35. Thesystem of claim 34, wherein the power control bit sequence comprisespower control bits for the mobile stations according to the powercontrol information of the mobile stations.
 36. The system of claim 35,wherein the power control bits for the mobile stations comprise a changein a power level by a threshold from a transmission power level usedwhen the mobile stations transmit channel information to the basestation.
 37. The system of claim 28, wherein the message is a MediumAccess Control (MAC) message including a power control bit sequencegenerated according to the power control information.
 38. The system ofclaim 37, wherein the power control bit sequence comprises power controlbits for the mobile stations according to the power control informationof the mobile stations.
 39. The system of claim 38, wherein the powercontrol bits for the mobile stations comprise a change in a power levelby a threshold from a transmission power level used when the mobilestations transmit channel information to the base station.
 40. Thesystem of claim 28, wherein the message comprises allocation informationof channels allocated to receive the channel information.
 41. A systemfor controlling power in a communication system, the system comprising:a mobile station for receiving a message including power controlinformation from a base station, detecting power control informationincluded in the message, and detecting power control informationcorresponding to thereto from the detected power control informationaccording to allocation information of a channel allocated to transmitchannel information of the mobile station to the base station.
 42. Thesystem of claim 41, wherein the allocation information comprises anindex including a unique number and allocation order of the allocatedchannel.
 43. The system of claim 41, wherein the mobile station checks asub-field corresponding to the mobile station according to allocationinformation of the allocated channel among a plurality of sub-fieldsallocated to transmit power control information of other mobile stationsincluding the mobile station, and detects power control information ofthe mobile station transmitted over the checked sub-field.
 44. Thesystem of claim 43, wherein the mobile station checks a sub-fieldcorresponding to the mobile station according to a unique number andallocation order of the allocated channel.
 45. The system of claim 41,wherein the message is a MAP message including a power control bitsequence generated according to the power control information.
 46. Thesystem of claim 45, wherein the power control bit sequence comprises apower control bit for the mobile station according to the power controlinformation of the mobile station.
 47. The system of claim 46, whereinthe power control bit for the mobile station comprises a change in apower level by a threshold from a transmission power level used when themobile station transmits channel information to the base station. 48.The system of claim 41, wherein the message is a Medium Access Control(MAC) message including a power control bit sequence generated accordingto the power control information.
 49. The system of claim 48, whereinthe power control bit sequence comprises a power control bit for themobile station according to the power control information of the mobilestation.
 50. The system of claim 49, wherein the power control bit forthe mobile station comprises a change in a power level by a thresholdfrom a transmission power level used when the mobile station transmitschannel information to the base station.
 51. The system of claim 41,wherein the message comprises allocation information of a channelallocated to receive the channel information.
 52. A system forcontrolling power in a communication system, the system comprising: abase station including; a power control information generator forreceiving channel information from a plurality of mobile stations, andgenerating power control information of the mobile stations according tothe received channel information; a channel allocator for allocatingchannels to the mobile stations to receive the channel information; apower control bit sequence generator for mapping the generated powercontrol information to transmission fields of corresponding mobilestations according to allocation information of the allocated channels,and generating a power control bit sequence according to the powercontrol information mapped to the transmission fields of thecorresponding mobile stations; and a message generator for generating amessage including the generated power control bit sequence; wherein thebase station broadcasts the generated message to the mobile stations.53. The system of claim 52, wherein the power control bit sequencegenerator divides the transmission fields of the power controlinformation into a plurality of sub-fields according to allocationinformation of the allocated channels, allocates the sub-fields to thecorresponding mobile stations, and maps the generated power controlinformation to the transmission fields of the mobile stations.
 54. Thesystem of claim 53, wherein the power control bit sequence generatordetermines a field for transmitting power control information of thecorresponding mobile stations among the sub-fields according to theallocation information of the allocated channels, and allocates thesub-fields to the corresponding mobile stations.
 55. The system of claim53, wherein the power control bit sequence generator divides onetransmission field into as many sub-fields as a number of the mobilestations.
 56. The system of claim 53, wherein the allocation informationcomprises indexes including unique numbers and allocation orders of theallocated channels.
 57. The system of claim 53, wherein the base stationallocates the sub-fields to the corresponding mobile stations accordingto unique numbers and allocation orders of the allocated channels. 58.The system of claim 52, wherein the message is a MAP message including apower control bit sequence generated according to the power controlinformation.
 59. The system of claim 58, wherein the power control bitsequence comprises power control bits for the mobile stations accordingto the power control information of the mobile stations.
 60. The systemof claim 59, wherein the power control bits for the mobile stationscomprise a change in a power level by a threshold from a transmissionpower level used when the mobile stations transmit channel informationto the base station.
 61. The system of claim 52, wherein the message isa Medium Access Control (MAC) message including a power control bitsequence generated according to the power control information.
 62. Thesystem of claim 61, wherein the power control bit sequence comprisespower control bits for the mobile stations according to the powercontrol information of the mobile stations.
 63. The system of claim 62,wherein the power control bits for the mobile stations comprise a changein a power level by a threshold from a transmission power level usedwhen the mobile stations transmit channel information to the basestation.
 64. The system of claim 52, wherein the message comprisesallocation information of channels allocated to receive the channelinformation.
 65. A system for controlling power in a communicationsystem, the system comprising: a mobile station including; a firstdetector for receiving a message including power control informationfrom a base station, and detecting the power control informationincluded in the message; a decider for checking allocation informationof a channel allocated to transmit channel information of the mobilestation to the base station; and a second detector for detecting, fromthe detected power control information, power control informationcorresponding thereto according to allocation information of theallocated channel; wherein the mobile station controls power of themobile station according to the power control information detected bythe second detector.
 66. The system of claim 65, wherein the allocationinformation comprises an index including a unique number and allocationorder of the allocated channel.
 67. The system of claim 65, wherein thesecond detector checks a sub-field corresponding to the mobile stationaccording to allocation information of the allocated channel among aplurality of sub-fields allocated to transmit power control informationof other mobile stations including the mobile station, and detects powercontrol information of the mobile station transmitted over the checkedsub-field.
 68. The system of claim 67, wherein the second detectorchecks a sub-field corresponding to the mobile station according to aunique number and allocation order of the allocated channel.
 69. Thesystem of claim 65, wherein the message is a MAP message including apower control bit sequence generated according to the power controlinformation.
 70. The system of claim 69, wherein the power control bitsequence comprises a power control bit for the mobile station accordingto the power control information of the mobile station.
 71. The systemof claim 70, wherein the power control bit for the mobile stationcomprises a change in a power level by a threshold from a transmissionpower level used when the mobile station transmits channel informationto the base station.
 72. The system of claim 65, wherein the message isa Medium Access Control (MAC) message including a power control bitsequence generated according to the power control information.
 73. Thesystem of claim 72, wherein the power control bit sequence comprises apower control bit for the mobile station according to the power controlinformation of the mobile station.
 74. The system of claim 73, whereinthe power control bit for the mobile station comprises a change in apower level by a threshold from a transmission power level used when themobile station transmits channel information to the base station. 75.The system of claim 65, wherein the message comprises allocationinformation of a channel allocated to receive the channel information.